Friction material

ABSTRACT

A friction apparatus such as a brake or clutch includes a rotor formed from an aluminum alloy and hardened with a ceramic reinforcing material and a component such as a brake pad having a friction surface which incorporates a hard inorganic material which is an oxide, carbide, or nitride in an amount of 0.5 to 15% by volume. The reinforcing agent in the aluminum alloy and the hardening material in the friction material are selected to be compatible in accordance with the teachings of the specification.

This application is a continuation of application Ser. No. 08/365,607filed Dec. 28, 1994, now abandoned, which application is acontinuation-in-part of Ser. No. 08/234,114, filed Apr. 28, 1994, nowabandoned.

FIELD OF THE INVENTION

The present invention relates to combinations of friction materials andhardened aluminum surfaces which are mutually compatible. The inventionis applicable to disc and drum brakes and to clutches in the automotiveand aircraft industries, and to machine tools generally. Selections ofcertain combinations of additives to the friction material and to thealuminum alloy have been found to provide an excellent coefficient offriction with low rates of wear to the friction material and to thealuminum surface.

PRIOR ART

Weight reduction is very desirable in the automotive industry and in theaircraft industry. The necessity for weight reduction in aircraft isobvious. Weight reduction in the automotive and trucking industries hasbecome more important as the cost of fuel, the tax rate on the fuel andthe stringency of environmental regulations increases. Historically,brake drums, brake rotors and flywheels have been formed of cast iron.Brake shoes, disc pads and clutches have been faced with compositionsincluding binders, fillers, metal flakes and asbestos fibers. Variouscombinations have been employed to provide a suitable coefficient offriction at low temperatures while minimizing wear and fading tendenciesat higher temperatures. The use of asbestos has diminished greatly inmany countries as a result of environmental and occupational healthregulations.

The desire to reduce unsprung weight and overall vehicle weight suggeststhat aluminum alloys would be a suitable substitute for cast iron.Unfortunately, aluminum alloys are softer than cast iron and the wearrates encountered when using conventional friction materials areunacceptable.

Aluminum alloys may be effectively hardened by adding particles orwhiskers of ceramic materials such as SiC, Al₂ O₃ or ZrO₂, but liningsof the conventional type formed from a binder such as a phenolic resin,a filler such as graphite, barium sulfate, calcium carbonate and/ormetal powder, and a fibrous material other than asbestos, i.e., organicfibers, glass fibers, or metallic fibers, are incompatible with thehardened aluminum alloys. Particularly, the coefficient of friction istoo low or the rate of attack of the friction material on the aluminumis unacceptable. A different approach appears to be required.

BRIEF SUMMARY OF THE INVENTION

It has been found that friction materials which contain certain hardinorganic materials such as metal oxides, borides, carbides, and/ornitrides, such materials having a Mohs' hardness of 8 or greater, areespecially compatible with aluminum alloy metal surfaces which arehardened with certain interstitial ceramic materials. The selection ofthe appropriate combination of ceramic hardening agent for the aluminumalloy and hard inorganic additive to the friction material follows asemi-empirical pattern.

DETAILED DESCRIPTION OF THE INVENTION

The friction material according to this invention is characterized bycontaining a hard, inorganic material in conjunction with binders,fillers and fibrous reinforcements characteristic of conventionalfriction materials.

The hard inorganic materials used in the friction material according tothis invention, must have a Mohs' hardness of 8 or greater. The apparentreason for this requirement is that the hardening agents used in thecompatible aluminum alloys have a comparable Mohs' hardness.

The hard inorganic material having a Mohs' hardness of 8 or more, can bea metal oxide, such as ZrO₂ or Al₂ O₃, a boride such as B₄ C, a carbidesuch as SiC or WC, a nitride, such as c-BN and mixtures thereof.

The hard inorganic material can be in the form of a powder, a particleor a whisker. Different forms are generally compatible.

The size of the hard inorganic material is preferably between 0.2 and250 μm when the material is in the form of a powder or particle. Sizessmaller than 0.2 μm are not sufficiently abrasive and fail to provide asufficiently high coefficient of friction. Sizes greater than 250 μmtend to be too abrasive and, more importantly, tend to gouge the surfaceof the aluminum material.

When the hard inorganic material is a whisker or fiber, suitablediameters are from 0.1 to 100 μm in lengths of 1 μm to 5 mm for reasonsas described above.

The amount of the hard, inorganic material in the friction material isdesirably about 0.1 to 30% by volume, preferably 0.5-15%. Amounts lessthan 0.1% do not achieve any significant improvement in the coefficientof friction. Amounts greater than 30% produce a roughness which exceedsthe hardness improvement in the aluminum alloy as described below andcause excessive wear of the alloy.

The hardening or reinforcing material for the aluminum alloy is used inan amount of 35 vol % or less and, preferably, 15 to 25% vol %, and is aceramic in the form of particles, whiskers or the like selected from Si₃N₄, TiN, TiC, Al₂ O₃, SiC, ZrO₂, SiO₂ and mixtures thereof.

The formulation of the aluminum alloy containing the hardening orreinforcing material begins with a conventional aluminum alloy selectedfrom those compositions disclosed in Japanese Industrial Standards andequivalent compositions well known to those in the art. A preferredaluminum alloy contains 65 vol % to 98 vol % of aluminum. The hardeningmaterial, in the form of particles, whiskers, or powders, can be addedto the molten alloy or applied by procedures suitable for introducingceramic particles into the surface of a pre-formed blank or partiallymachined material. For example, particles can be introduced using aplasma torch or by application of the particles, followed by scanningthe surface with a laser. The particles do not become part of a liquidsolution, but remains as discrete particles entrapped in the aluminumalloy matrix. These ceramic materials are the same as, or haveproperties similar to, the hard, inorganic materials used in thefriction material. The following Tables illustrate the materials and therelationships in terms of percent by volume which produce the compatiblehardened alloys and friction materials according to this invention.

                  TABLE 1A                                                        ______________________________________                                        H in AR     Si.sub.3 N.sub.4                                                                          Si.sub.3 N.sub.4                                                                         Si.sub.3 N.sub.4                                       0.5˜10                                                                              5˜20 15˜35                                H in FM     SiC         SiC        SiC                                                    0.5˜10                                                                              3˜12 5˜15                                 H in AR     Si.sub.3 N.sub.4                                                                          Si.sub.3 N.sub.4                                                                         Si.sub.3 N.sub.4                                       0.5˜10                                                                              5˜20 15˜35                                H in FM     Al.sub.2 O.sub.3                                                                          Al.sub.2 O.sub.3                                                                         Al.sub.2 O.sub.3                                       0.5˜10                                                                              3˜12 5˜15                                 H in AR     Si.sub.3 N.sub.4                                                                          Si.sub.3 N.sub.4                                                                         Si.sub.3 N.sub.4                                       0.5˜10                                                                              5˜20 15˜35                                H in FM     ZrO.sub.2   ZrO.sub.2  ZrO.sub.2                                              1.0˜10                                                                              3˜12 5˜15                                 H in AR     Si.sub.3 N.sub.4                                                                          Si.sub.3 N.sub.4                                                                         Si.sub.3 N.sub.4                                       0.5˜10                                                                              5˜20 15˜35                                H in FM     B.sub.4 C   B.sub.4 C  B.sub.4 C                                              0.5˜10                                                                              3˜12 5˜15                                 H in AR     Si.sub.3 N.sub.4                                                                          Si.sub.3 N.sub.4                                                                         Si.sub.3 N.sub.4                                       0.5˜10                                                                              5˜20 15˜35                                H in FM     c-BN        c-BN       c-BN                                                   0.5˜10                                                                              3˜12 5˜15                                 H in AR     Si.sub.3 N.sub.4                                                                          Si.sub.3 N.sub.4                                                                         Si.sub.3 N.sub.4                                       0.5˜10                                                                              5˜20 15˜35                                H in FM     WC          WC         WC                                                     0.5˜10                                                                              3˜12 5˜15                                 ______________________________________                                    

                  TABLE 1B                                                        ______________________________________                                        H in AR     TiN         TiN        TiN                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     SiC         SiC        SiC                                                    0.5˜10                                                                              3˜12 5˜15                                 H in AR     TiN         TiN        TiN                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     Al.sub.2 O.sub.3                                                                          Al.sub.2 O.sub.3                                                                         Al.sub.2 O.sub.3                                       0.5˜10                                                                              3˜12 5˜15                                 H in AR     TiN         TiN        TiN                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     ZrO.sub.2   ZrO.sub.2  ZrO.sub.2                                              1.0˜10                                                                              3˜12 5˜15                                 H in AR     TiN         TiN        TiN                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     B.sub.4 C   B.sub.4 C  B.sub.4 C                                              0.5˜10                                                                              3˜12 5˜15                                 H in AR     TiN         TiN        TiN                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     c-BN        c-BN       c-BN                                                   0.5˜10                                                                              3˜12 5˜15                                 H in AR     TiN         TiN        TiN                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     WC          WC         WC                                                     0.5˜10                                                                              3˜12 5˜15                                 ______________________________________                                    

                  TABLE 1C                                                        ______________________________________                                        H in AR     TiC         TiC        TiC                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     SiC         SiC        SiC                                                    1.0˜10                                                                              3˜12 5˜15                                 H in AR     TiC         TiC        TiC                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     Al.sub.2 O.sub.3                                                                          Al.sub.2 O.sub.3                                                                         Al.sub.2 O.sub.3                                       1.0˜10                                                                              3˜12 5˜15                                 H in AR     TiC         TiC        TiC                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     ZrO.sub.2   ZrO.sub.2  ZrO.sub.2                                              2˜10  4˜12 6˜15                                 H in AR     TiC         TiC        TiC                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     B.sub.4 C   B.sub.4 C  B.sub.4 C                                              1.0˜10                                                                              3˜12 5˜15                                 H in AR     TiC         TiC        TiC                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     c-BN        c-BN       c-BN                                                   1.0˜10                                                                              3˜12 5˜15                                 H in AR     TiC         TiC        TiC                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     WC          WC         WC                                                     1.0˜10                                                                              3˜12 5˜15                                 ______________________________________                                    

                  TABLE 1D                                                        ______________________________________                                        H in AR     Al.sub.2 O.sub.3                                                                          Al.sub.2 O.sub.3                                                                         Al.sub.2 O.sub.3                                       0.5˜10                                                                              5˜20 15˜35                                H in FM     SiC         SiC        SiC                                                    0.1˜7 2˜11 3˜12                                 H in AR     Al.sub.2 O.sub.3                                                                          Al.sub.2 O.sub.3                                                                         Al.sub.2 O.sub.3                                       0.5˜10                                                                              5˜20 15˜35                                H in FM     Al.sub.2 O.sub.3                                                                          Al.sub.2 O.sub.3                                                                         Al.sub.2 O.sub.3                                       0.1˜8 2˜12 3˜15                                 H in AR     Al.sub.2 O.sub.3                                                                          Al.sub.2 O.sub.3                                                                         Al.sub.2 O.sub.3                                       0.5˜10                                                                              5˜20 15˜35                                H in FM     ZrO.sub.2   ZrO.sub.2  ZrO.sub.2                                              0.5˜10                                                                              2˜12 5˜15                                 H in AR     Al.sub.2 O.sub.3                                                                          Al.sub.2 O.sub.3                                                                         Al.sub.2 O.sub.3                                       0.5˜10                                                                              5˜20 15˜35                                H in FM     B.sub.4 C   B.sub.4 C  B.sub.4 C                                              0.1˜8 2˜12 3˜15                                 H in AR     Al.sub.2 O.sub.3                                                                          Al.sub.2 O.sub.3                                                                         Al.sub.2 O.sub.3                                       0.5˜10                                                                              5˜20 15˜35                                H in FM     c-BN        c-BN       c-BN                                                   0.1˜8 2˜12 3˜15                                 H in AR     Al.sub.2 O.sub.3                                                                          Al.sub.2 O.sub.3                                                                         Al.sub.2 O.sub.3                                       0.5˜10                                                                              5˜20 15˜35                                H in FM     WC          WC         WC                                                     0.1˜7 2˜11 3˜12                                 ______________________________________                                    

                  TABLE 1E                                                        ______________________________________                                        H in AR     SiC         SiC        SiC                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     SiC         SiC        SiC                                                    0.1˜8 2˜12 3˜15                                 H in AR     SiC         SiC        SiC                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     Al.sub.2 O.sub.3                                                                          Al.sub.2 O.sub.3                                                                         Al.sub.2 O.sub.3                                       0.1˜8 2˜12 3˜15                                 H in AR     SiC         SiC        SiC                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     ZrO.sub.2   ZrO.sub.2  ZrO.sub.2                                              0.5˜10                                                                              2˜12 5˜15                                 H in AR     SiC         SiC        SiC                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     B.sub.4 C   B.sub.4 C  B.sub.4 C                                              0.1˜8 2˜12 3˜15                                 H in AR     SiC         SiC        SiC                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     c-BN        c-BN       c-BN                                                   0.1˜8 2˜12 3˜15                                 H in AR     SiC         SiC        SiC                                                    0.5˜10                                                                              5˜20 15˜35                                H in FM     WC          WC         WC                                                     0.1˜8 2˜12 3˜15                                 ______________________________________                                    

                  TABLE 1F                                                        ______________________________________                                        H in AR  ZrO.sub.2 --SiO.sub.2                                                                      ZrO.sub.2 --SiO.sub.2                                                                   ZrO.sub.2 --SiO.sub.2                                  0.5˜10  5˜20                                                                             15˜35                                   H in FM  SiC          SiC       SiC                                                    0.1˜5  2˜8  3˜12                                   H in AR  ZrO.sub.2 --SiO.sub.2                                                                      ZrO.sub.2 --SiO.sub.2                                                                   ZrO.sub.2 --SiO.sub.2                                  0.5˜10  5˜20                                                                             15˜35                                   H in FM  Al.sub.2 O.sub.3                                                                           Al.sub.2 O.sub.3                                                                        Al.sub.2 O.sub.3                                       0.1˜5  2˜8  3˜12                                   H in AR  ZrO.sub.2 --SiO.sub.2                                                                      ZrO.sub.2 --SiO.sub.2                                                                   ZrO.sub.2 --SiO.sub.2                                  0.5˜10  5˜20                                                                             15˜35                                   H in FM  ZrO.sub.2    ZrO.sub.2 ZrO.sub.2                                              0.1˜8   2˜12                                                                              3˜15                                   H in AR  ZrO.sub.2 --SiO.sub.2                                                                      ZrO.sub.2 --SiO.sub.2                                                                   ZrO.sub.2 --SiO.sub.2                                  0.5˜10  5˜20                                                                             15˜35                                   H in FM  B.sub.4 C    B.sub.4 C B.sub.4 C                                              0.1˜5  2˜8  3˜12                                   H in AR  ZrO.sub.2 --SiO.sub.2                                                                      ZrO.sub.2 --SiO.sub.2                                                                   ZrO.sub.2 --SiO.sub.2                                  0.5˜10  5˜20                                                                             15˜35                                   H in FM  c-BN         c-BN      c-BN                                                   0.1˜5  2˜8  3˜12                                   H in AR  ZrO.sub.2 --SiO.sub.2                                                                      ZrO.sub.2 --SiO.sub.2                                                                   ZrO.sub.2 --SiO.sub.2                                  0.5˜10  5˜20                                                                             15˜35                                   H in FM  WC           WC        WC                                                     0.1˜5  2˜8  3˜12                                   ______________________________________                                    

The symbol "H in AR" indicates the hard reinforcing material and itspercentage in an aluminum rotor. The symbol "H in FM" indicates the hardinorganic material and its percentage in the friction material.

The following examples illustrate the effectiveness of the disclosedinvention. The examples are purely illustrative and not limitative ofthe scope of the invention. Modifications to the invention which areapparent to those of skill in the art are included within the scope ofthe invention.

EXAMPLES 1-5 AND COMPARATIVE EXAMPLE 1

Friction materials of Examples 1-5 and Comparative Example 1 wereproduced under the following conditions.

Preliminary moldings:

room temperature, face pressure=400 kg/cm²

Hot pressing:

temp.=150° C., pressure=400 kg/cm², 10 minutes

Heat treatment: 180° C.×5 hours

The obtained friction materials were subjected to a friction test usinga full-size dynamometer, under the following conditions:

Test method: JASO C427-83 I=5 kgms²

Rotor material: matrix=aluminum alloy of JIS AC8B

Reinforcing agent of rotor:

SiC particles of 15 μm, used in an amount of 20% by volume The resultsare shown in Table 1.

                  TABLE 1                                                         ______________________________________                                                                         Comp                                         Composition of friction                                                                     Examples           Ex.                                          material (vol. %)                                                                           1      2      3    4    5    1                                  ______________________________________                                        Aramid fiber  10     10     10   10   10   10                                 Brass fiber   10     10     10   10   10   10                                 Phenolic resin                                                                              20     20     20   20   20   20                                 Graphite      15     15     15   15   15   15                                 Friction controlling agent                                                                  20     20     20   20   20   20                                 Inorganic filler                                                                            10     10     10   10   10   10                                 (barium sulfate)                                                              Inorganic filler                                                                             5     10     10    5    0   15                                 (calcium carbonate)                                                           Hard inorganic material                                                       SiC particles (dia. = 1 μm)                                                              10                  5    5                                      SiC particles (dia. = 15 μm)                                                                     5                5                                      Al.sub.2 O.sub.3 particles   5                                                (dia. = 15 μm)                                                             SiC whiskers                      5    5                                      Friction test results                                                         Friction coefficient (μ)                                                   100° C.                                                                              0.36   0.38   0.37 0.38 0.41 0.21                               200° C.                                                                              0.41   0.37   0.38 0.43 0.43 0.24                               300° C.                                                                              0.38   0.36   0.36 0.37 0.38 0.28                               Wear amount (mm)                                                              100° C.                                                                              0.3    0.4    0.3  0.3  0.3  0.8                                300° C.                                                                              0.5    0.3    0.5  0.2  0.1  1.4                                Attack to opposite face                                                       (μm)                                                                       100° C.                                                                              2      3      2    2    1    -5                                 300° C.                                                                              1      2      3    4    2    -16                                ______________________________________                                    

In Table 1, a minus value indicates that in the attack to the opposingface powder is generated by wear and adhered onto said opposing face.

As is clear from Table 1, the friction materials of the presentinvention each containing a hard inorganic material show excellentcoefficients of friction and excellent wear resistance over a widetemperature range and are superior in lack of attack to the opposingface. In contrast, the friction material of Comparative Example 1 isinferior in friction coefficient and wear resistance and was ground bythe opposing face.

In addition to the materials which have been described above, it isunderstood that friction control agents including MoS₂, Sb₂ S₃, Sb₂ O₃,rubber powder, graphite, pulverized nutshells, and other additives knownto those skilled in the art may be employed to provide the coefficientof friction required for a particular utilization. It is likewiseunderstood that mechanical systems not related to the transportationindustry may also find the combination of specified friction materialand hardened aluminum alloy suitable for their uses.

We claim:
 1. A friction apparatus comprising (1) an element comprisingan aluminum alloy reinforced with at least one hard ceramic material,and (2) a friction material for friction coupling with said element andcontaining at least one hard material additive,wherein said aluminumalloy contains 65 volume % to 98 volume % of aluminum, and 0.5 volume %to 35 volume % of hard reinforcing material selected from the groupconsisting of Si₃ N₄, TiN, TiC, Al₂ O₃, SiC, ZrO₂, and SiO₂, and whereinsaid friction material contains 0.1 volume % to 30 volume % of a hardinorganic material selected from the group consisting of SiC, Al₂ O₃,ZrO₂, B₄ C, c-BN and WC.
 2. A friction apparatus according to claim 1,wherein said hard inorganic material contained in said friction materialhas the form of a powder, particle or whisker.
 3. A friction apparatusaccording to claim 1, wherein said hard inorganic material contained inthe friction material has a Mohs hardness of at least
 8. 4. A frictionapparatus according to claim 1, wherein the hard inorganic materialcontained in the friction material is SiC.
 5. A friction apparatusaccording to claim 1, wherein the hard inorganic material contained inthe friction material is Al₂ O₃.
 6. A friction apparatus according toclaim 1, wherein the hard inorganic material in the friction material ispresent in an amount of from 0.5 volume % to 15 volume %.
 7. A brakingapparatus comprising a rotor which is formed from an aluminum alloyhardened with between 0.5 volume % and 35 volume % of a materialselected from the group consisting of Si₃ N₄, TiN, TiC, Al₂ O₃, SiC,ZrO₂, and SiO₂ and combinations thereof, and a stator for frictioncoupling with said rotor and having an outer surface having a frictionmaterial thereon, the friction material containing 0.5 volume % to 15volume % of a hardening material selected from the group consisting ofSiC, Al₂ O₃, ZrO₂, B₄ C, c-BN, and WC, wherein each relationship betweenthe identity and amount in terms of volume % of a hardening agent in therotor, H in AR, and the identity and amount in terms of volume % of ahardening material in the friction material, H in FM, is defined inTables 1A, 1B, 1C, 1D, 1E, and 1F as follows:

                  TABLE 1A                                                        ______________________________________                                        H in AR  Si.sub.3 N.sub.4                                                                            Si.sub.3 N.sub.4                                                                      Si.sub.3 N.sub.4                                        0.5˜10   5˜20                                                                           15˜35                                    H in FM  SiC           SiC     SiC                                                     0.5˜10   3˜12                                                                            5˜15                                    H in AR  Si.sub.3 N.sub.4                                                                            Si.sub.3 N.sub.4                                                                      Si.sub.3 N.sub.4                                        0.5˜10   5˜20                                                                           15˜35                                    H in FM  Al.sub.2 O.sub.3                                                                            Al.sub.2 O.sub.3                                                                      Al.sub.2 O.sub.3                                        0.5˜10   3˜12                                                                            5˜15                                    H in AR  Si.sub.3 N.sub.4                                                                            Si.sub.3 N.sub.4                                                                      Si.sub.3 N.sub.4                                        0.5˜10   5˜20                                                                           15˜35                                    H in FM  ZrO.sub.2     ZrO.sub.2                                                                             ZrO.sub.2                                               1.0˜10   3˜12                                                                            5˜15                                    H in AR  Si.sub.3 N.sub.4                                                                            Si.sub.3 N.sub.4                                                                      Si.sub.3 N.sub.4                                        0.5˜10   5˜20                                                                           15˜35                                    H in FM  B.sub.4 C     B.sub.4 C                                                                             B.sub.4 C                                               0.5˜10   3˜12                                                                            5˜15                                    H in AR  Si.sub.3 N.sub.4                                                                            Si.sub.3 N.sub.4                                                                      Si.sub.3 N.sub.4                                        0.5˜10   5˜20                                                                           15˜35                                    H in FM  c-BN          c-BN    c-BN                                                    0.5˜10   3˜12                                                                            5˜15                                    H in AR  Si.sub.3 N.sub.4                                                                            Si.sub.3 N.sub.4                                                                      Si.sub.3 N.sub.4                                        0.5˜10   5˜20                                                                           15˜35                                    H in FM  WC            WC      WC                                                      0.5˜10   3˜12                                                                            5˜15                                    ______________________________________                                    

                  TABLE 1B                                                        ______________________________________                                        H in AR  TiN           TiN     TiN                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  SiC           SiC     SiC                                                     0.5˜10   3˜12                                                                            5˜15                                    H in AR  TiN           TiN     TiN                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  Al.sub.2 O.sub.3                                                                            Al.sub.2 O.sub.3                                                                      Al.sub.2 O.sub.3                                        0.5˜10   3˜12                                                                            5˜15                                    H in AR  TiN           TiN     TiN                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  ZrO.sub.2     ZrO.sub.2                                                                             ZrO.sub.2                                               1.0˜10   3˜12                                                                            5˜15                                    H in AR  TiN           TiN     TiN                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  B.sub.4 C     B.sub.4 C                                                                             B.sub.4 C                                               0.5˜10   3˜12                                                                            5˜15                                    H in AR  TiN           TiN     TiN                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  c-BN          c-BN    c-BN                                                    0.5˜10   3˜12                                                                            5˜15                                    H in AR  TiN           TiN     TiN                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  WC            WC      WC                                                      0.5˜10   3˜12                                                                            5˜15                                    ______________________________________                                    

                  TABLE 1C                                                        ______________________________________                                        H in AR  TiC           TiC     TiC                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  SiC           SiC     SiC                                                     1.0˜10   3˜12                                                                            5˜15                                    H in AR  TiC           TiC     TiC                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  Al.sub.2 O.sub.3                                                                            Al.sub.2 O.sub.3                                                                      Al.sub.2 O.sub.3                                        1.0˜10   3˜12                                                                            5˜15                                    H in AR  TiC           TiC     TiC                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  ZrO.sub.2     ZrO.sub.2                                                                             ZrO.sub.2                                                2˜10    4˜12                                                                            6˜15                                    H in AR  TiC           TiC     TiC                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  B.sub.4 C     B.sub.4 C                                                                             B.sub.4 C                                               1.0˜10   3˜12                                                                            5˜15                                    H in AR  TiC           TiC     TiC                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  c-BN          c-BN    c-BN                                                    1.0˜10   3˜12                                                                            5˜15                                    H in AR  TiC           TiC     TiC                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  WC            WC      WC                                                      1.0˜10   3˜12                                                                            5˜15                                    ______________________________________                                    

                  TABLE 1D                                                        ______________________________________                                        H in AR  Al.sub.2 O.sub.3                                                                            Al.sub.2 O.sub.3                                                                      Al.sub.2 O.sub.3                                        0.5˜10   5˜20                                                                           15˜35                                    H in FM  SiC           SiC     SiC                                                     0.1˜7    2˜11                                                                            3˜12                                    H in AR  Al.sub.2 O.sub.3                                                                            Al.sub.2 O.sub.3                                                                      Al.sub.2 O.sub.3                                        0.5˜10   5˜20                                                                           15˜35                                    H in FM  Al.sub.2 O.sub.3                                                                            Al.sub.2 O.sub.3                                                                      Al.sub.2 O.sub.3                                        0.1˜8    2˜12                                                                            3˜15                                    H in AR  Al.sub.2 O.sub.3                                                                            Al.sub.2 O.sub.3                                                                      Al.sub.2 O.sub.3                                        0.5˜10   5˜20                                                                           15˜35                                    H in FM  ZrO.sub.2     ZrO.sub.2                                                                             ZrO.sub.2                                               0.5˜10   2˜12                                                                            5˜15                                    H in AR  Al.sub.2 O.sub.3                                                                            Al.sub.2 O.sub.3                                                                      Al.sub.2 O.sub.3                                        0.5˜10   5˜20                                                                           15˜35                                    H in FM  B.sub.4 C     B.sub.4 C                                                                             B.sub.4 C                                               0.1˜8    2˜12                                                                            3˜15                                    H in AR  Al.sub.2 O.sub.3                                                                            Al.sub.2 O.sub.3                                                                      Al.sub.2 O.sub.3                                        0.5˜10   5˜20                                                                           15˜35                                    H in FM  c-BN          c-BN    c-BN                                                    0.1˜8    2˜12                                                                            3˜15                                    H in AR  Al.sub.2 O.sub.3                                                                            Al.sub.2 O.sub.3                                                                      Al.sub.2 O.sub.3                                        0.5˜10   5˜20                                                                           15˜35                                    H in FM  WC            WC      WC                                                      0.1˜7    2˜11                                                                            3˜12                                    ______________________________________                                    

                  TABLE 1E                                                        ______________________________________                                        H in AR  SiC           SiC     SiC                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  SiC           SiC     SiC                                                     0.1˜8    2˜12                                                                            3˜15                                    H in AR  SiC           SiC     SiC                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  Al.sub.2 O.sub.3                                                                            Al.sub.2 O.sub.3                                                                      Al.sub.2 O.sub.3                                        0.1˜8    2˜12                                                                            3˜15                                    H in AR  SiC           SiC     SiC                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  ZrO.sub.2     ZrO.sub.2                                                                             ZrO.sub.2                                               0.5˜10   2˜12                                                                            5˜15                                    H in AR  SiC           SiC     SiC                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  B.sub.4 C     B.sub.4 C                                                                             B.sub.4 C                                               0.1˜8    2˜12                                                                            3˜15                                    H in AR  SiC           SiC     SiC                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  c-BN          c-BN    c-BN                                                    0.1˜8    2˜12                                                                            3˜15                                    H in AR  SiC           SiC     SiC                                                     0.5˜10   5˜20                                                                           15˜35                                    H in FM  WC            WC      WC                                                      0.1˜8    2˜12                                                                            3˜15                                    ______________________________________                                    

                  TABLE 1F                                                        ______________________________________                                        H in AR    ZrO.sub.2 --SiO.sub.2                                                                     ZrO.sub.2 --SiO.sub.2                                                                     ZrO.sub.2 --SiO.sub.2                                 0.5˜10                                                                              5˜20  15˜35                                H in FM    SiC         SiC         SiC                                                   0.1˜5 2˜8   3˜12                                 H in AR    ZrO.sub.2 --SiO.sub.2                                                                     ZrO.sub.2 --SiO.sub.2                                                                     ZrO.sub.2 --SiO.sub.2                                 0.5˜10                                                                              5˜20  15˜35                                H in FM    Al.sub.2 O.sub.3                                                                          Al.sub.2 O.sub.3                                                                          Al.sub.2 O.sub.3                                      0.1˜5 2˜8   3˜12                                 H in AR    ZrO.sub.2 --SiO.sub.2                                                                     ZrO.sub.2 --SiO.sub.2                                                                     ZrO.sub.2 --SiO.sub.2                                 0.5˜10                                                                              5˜20  15˜35                                H in FM    ZrO.sub.2   ZrO.sub.2   ZrO.sub.2                                             0.1˜8 2˜12  3˜15                                 H in AR    ZrO.sub.2 --SiO.sub.2                                                                     ZrO.sub.2 --SiO.sub.2                                                                     ZrO.sub.2 --SiO.sub.2                                 0.5˜10                                                                              5˜20  15˜35                                H in FM    B.sub.4 C   B.sub.4 C   B.sub.4 C                                             0.1˜5 2˜8   3˜12                                 H in AR    ZrO.sub.2 --SiO.sub.2                                                                     ZrO.sub.2 --SiO.sub.2                                                                     ZrO.sub.2 --SiO.sub.2                                 0.5˜10                                                                              5˜20  15˜35                                H in FM    c-BN        c-BN        c-BN                                                  0.1˜5 2˜8   3˜12                                 H in AR    ZrO.sub.2 --SiO.sub.2                                                                     ZrO.sub.2 --SiO.sub.2                                                                     ZrO.sub.2 --SiO.sub.2                                 0.5˜10                                                                              5˜20  15˜35                                H in FM    WC          WC          WC                                                    0.1˜5 2˜8   3˜12                                 ______________________________________                                    


8. A braking apparatus according to claim 1, wherein the aluminum alloyis hardened with from 15 volume % to 25 volume % of SiC, and thefriction material contains a hard material selected from the groupconsisting of SiC particles, Al₂ O₃ particles, and SiC whiskers.
 9. Afriction apparatus according to claim 1, wherein the element is a rotor.10. A friction apparatus according to claim 1, wherein the element is adrum.